The extreme heat has been taking a toll on the rail lines, leading to commuting delays for riders.

New Jersey Transit posted alerts talking about “equipment issues,” which News 12 has learned were largely related to riders' comfort.

New Jersey Transit CEO Kris Kolluri says air conditioning inside rail cars had been breaking down.

“We don’t let a train leave the station if the air conditioning unit is not working. That could lead to a lot more challenges," said Kolluri. “When you have temperatures that go to 110 degrees the most important thing for us is to make sure that the air conditioning units are working,” said Kolluri.

Kolluri says temperatures underneath Newark Penn Station, where trains are waiting for riders, can rise to 128 degrees.

The AC units aren’t the only equipment that suffers in the heat - the actual rails expand, too.

Trains then have to slow down for safety and to prevent damaging the tracks.

Regular riders likely saw the alerts on social media, warning of the heat and apologizing for HVAC issues.

Kolluri says new equipment will reduce these breakdowns and added that by 2031, the entire system will be modernized.